This invention relates to a method of writing data in an ID (identification) system in which, under the control of a host computer, data from a second device such as an ID controller or the like is transmitted via transmission means to a first device such as a data carrier which includes a memory such as an EE PROM (electrically erasable programmable read-only memory) and is written in the memory, or data is read out of the memory and is transmitted from the first device to the second device via the transmission means.
ID systems are available for identifying the types of assembly parts, manufactured parts, semi-fabricated products delivered on a conveyor or the type of tool on a machine tool, by way of example. One type of such an ID system which has recently been considered employs data carrier elements affixed to these articles. Each data carrier contains a memory in which specific data from a controller can be written or from which data can be read.
In this conventonal ID system, each data carrier is assigned an identification code indicative of the article, tool or the like to which the carrier is attached, and extremely important data is stored in the memory of the data carrier. For instance, such data may relate to the length, diameter and offset of a tool, the cumulative utilization time thereof, tool lifetime, amount of wear, etc. Destruction of these data must be avoided at all cost. In particular, in the execution of processing for writing new data in the memory, sufficient care must be taken to avoid erasing the old data store in the memory. For example, if a data storage area is mistakenly addressed or if a write error occurs, the old data will be lost and cannot be restored. Above all, if the data is data relating to the total utilization time of a tool, such old data is impossible to recover once lost.